A 3D camera is sometimes arranged in a vehicle to assist the vehicle driver, for example, to determine distances to a lead vehicle or another object. Such a 3D camera can consist in this context of, for example, a Time of Flight (ToF) camera, a stereo camera, a light-field camera or the like.
The 3D camera can determine distances to objects by emitting a modulated lightwave, detecting a corresponding reflected lightwave from the object and measuring the shift of the reflected lightwave in relation to the emitted lightwave. The distance can be calculated because the wavelength and speed of the light are known.
One problem for 3D cameras to determine distances is that vehicles often have different surfaces that reflect the light to different extents. For example, the body of a car with metallic paint may reflect light very well, while the windows of the same vehicle may reflect very little light. This can cause far too little light being reflected from certain objects to enable the 3D camera to make a reliable measurement. In the worst case, this can result in the object not being detected by the 3D camera, or in an erroneous assessment of the size of and/or distance to the object to be made. Alternatively, the 3D camera may determine that there is a plurality of separate objects.
Another problem with 3D cameras can arise when, for example, a person is situated in proximity to a vehicle, or when a group of people is walking across a crosswalk. The 3D camera can then have difficulty distinguishing the person and the vehicle, and may interpret them as a single coherent object.
Furthermore, a 3D camera can have difficulty determining whether an object is, for example, a pole or an (uncommonly narrow and straight-backed) person, or between a concrete obstacle and an animal. This can be a problem in an emergency situation where emergency braking in combination with evasive maneuvers need to be performed and objects lying ahead need to be assigned priorities.
It is clear that much remains to be done to improve the ranging and detection of objects by means of a 3D camera.